Dishwasher apparatus and method



E. s. STODDARD DIsHwAsHER APPARATUS AND METHOD 7 Sheets-Sheet 1 v fi-9. 30

March 4, 1958 Filed Sept. 29, 1953 March 4, 1958 E. s. sToDDARD DIsHwAsHER APPARATUS AND METHOD 7 Sheets-Sheet 2 Filed Sept. 29, 1953 lIlAlL A 'from/Ey March 4, 1958 E. s. sToDDARD DIsHwAsHER APPARATUS. AND METHOD '7 Sheets-Sheet 3 Filed Sept. 29, 1953 ATTORNEY Man-ch 4, 1958 E. s. STODDARD DISHWASHER APPARATUS AND METHOD- 7 Sheets-Sheet 4 Filed Sept. 29, 1953 rlll I c l cwwwwmr..

EDGAR A oR/VEY March 4, 1958 l E. s. STODDARD 2,825,565

DIsHwAsHER APPARATUS AND METHOD Filed sept. 29, 1953 'I shve'ts-sheet 5 Mmh 4 3953 E. s. STQDDARD 2,825,665

DISHWASHER APPARATUS AND METHOD Filed Sepi. 29, 19.53 7 SheetS-Shee'b 6 65 /A/ VEA/T05' `5gg 506,4@ s. STODDARD 5y EMMA/@MJ TTORNEY @Ich 4 1958 E. s. STODDARD DISHWASHER APPARATUS AND vxx/LTHOD 7 Sheets-Sheet 7 Filed Sept. 29, 1953 NRM NEM

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D H y R mm M N0 M E l 7 V5 ws. f H wm E y 5 huil/Wj @uw mm w Nw www www United States Patent C) DSHWASHER APPARATUS AND METHD Edgar S. Stoddard, Berwyn, lil., assigner to General Electric Company, a corporation of New York Appiication September 29, 1953, Serial No. 382,901

16 Ciams. (Cl. 134-25) This invention relates to dishwashing apparatus, and to methods or" washing dishes and the like.

it is an object of the invention to provide dishwashing apparatus embodying means vfor effecting a new cycle of operation for washing, rinsing, and drying dishes, cooking utensils, table silver and the like.

It is an object of the invention to provide dishwashing apparatus which wili produce superior cleaning results with less use of heated water than in present dishwashing machines.

it is another object or" the invention to provide dishwashing apparatus which wiil make more eticient use of detergent than present dishwashing machines.

It is an object of the invention to provide a method of washing dishes which will substantially eliminate the retention on the dishes and the like of soil which may have been redeposited during earlier stages of the dishwasher operation.

It is an object of the invention to provide a method of washing dishes which includes the steps of removing the gross soil from the dishes by washing with heated detergent solution, draining said solution from the apparatus and subsequently washing the dishes with a substantially equal quantity of unheated washing liquid of substantially equivalent detergent concentration.

it is another object of the invention to provide a method of washing dishes which includes the steps of washing the dishes a plurality of times with fresh charges of washing liquid of substantially equal detergent strength and then washing the dishes an additional number of times with charges of washing solution of successively lessened detergent strength without limitation as to the relative temperatures of the washing solution.

lt is still another object of the invention to provide a method ot' washing dishes which includes a plurality of washing and rinsing steps in which selected steps may use heated washing liquid and other steps may use unheated washing liquid.

It is a further object of the invention to provide a method of washing dishes in which at least one washing step is carried out with a detergent solution at a temperature e'ectively minimizing the precipitation of calcium carbonate or like hard water constituents from the washing liquid onto the dishes and the like.

Workers in the `dishwasher art know that a dishwasher user appears to judge thc perfomance of the machine mainly by the appearance of the washed glassware. Many of the complaints received by dishwasher manufacturers have to do with spotty or lmy glassware. It has been popular to ascribe this unclean glassware appearance to hard water and the precipitation on the glassware of calcium carbonate and other substantially insoluble components of such water. Unquestionably, such precipitation is a factor, but after extensive research, I have determined that a very large percentage of glassware spotting and of course spotting is present, although less noticeable, on chinaware and other opaque articles-results from redeposition of soil previously removed from the 2,825,665 Patented Mar. 4, 1958 articles by the detergent solution. Redeposition results from the inability of the detergent solution, during a single washing operation, to sequester and carry away all of the soil load, with the result that soil which separates from the solution is caught by articles in the vat, or ydeposits on the walls and bottom of the vat. I, therefore, employ a succession of washing operations, in each of which the temperature and detergent concentration of the detergent solution is adapted to the soil condition at the commencement of the washing operation.

in preferred embodiments of the invention, dishwashing apparatus which is conventional in many respects is arranged to carry out the plurality of washing operations with minimum expenditure of heated water and detergent. The method of washing dishes embodying the invention provides a cycle of operations which operates to remove loose soil from the dishes by a heated water spray rinse which is also eective to raise the temperature of animal fats in the food soil at least close to the softening or liquefaction point thereof; to wash the articles in a detergent solution having a temperature and detergent composition effective to complete the liquefaction and emulsifcation of the animal fats and to support the food soil yfor complete drainage from the machine; to rinse the articles with clear, heated water; to wash the articles a second time with a full strength detergent solution comprised of unheated water; to effect successive washes of the articles with detergent solutions comprised of approximately one-half of the eiuent from the immediately previous wash and one-half clear, unheated water; to provide a nal clear, heated water rinse; and to provide a subsequent drying period.

The advantages of such a cycle of operations are apparent. The gross soil, which may contain a large amount of animal fats, is subjected to the washing action of a detergent having a concentration capable of sequestering a large proportion of the soil, and a temperature which enables the detergent solution to hold and transport the soil load to the drain. The immediately succeeding clear, heated rinse disposes of food soil which may have dropped out of the detergent solution during passage to the drain and hence deposited on the Walls or base of the vat. Thus, a large amount of the total soil is removed during the first two operations. However, because of the heterogeneous nature of the contents of the dishwasher, and the large number of individual items, there is ample opportunity for a redeposition of food soil particles on the contents. The next wash operation permeates the Washing vat with another detergent solution of full detergent concentration. The sequestering effect of the solution is high. initially, the temperature of the solution is low because it is comprised of unheated water, but its temperature rises during the second washing operation by heat transfer from the vat and its contents, which had, at this stage of operation, been subjected to two heated water rinses and one heated water washing operation. Therefore, the capacity of the second washing solution to sequester and support the soil load as it existed at the commencement of the second Wash is entirely adequate. The remaining unheated water rinses, and wash operations with successively lessened detergent concentrations, are directed primarily to removing any redeposited particles of food soil. The vat and its contents have now given up their heat, and the detergent solutions have no appreciable temperature rise. The unheated solutions, however, are adequate to support and carry to the drain the relatively small amounts of food soil as yet undisposed of. It is important to note that unheated detergent solutions do not precipitate calcium carbonatos to any objectionable degree, thus preventing the spotting of the dishes and glassware from this source. The inal clean water rinse ushes away 'ice lthe ,last 'traces :'of ldetergent solution. lthou'g'h an 'unheated rinse would be adequate, the surface tension of heated water is less than that of unheated water, and by using a heated water final-.rinse I reduce the number of large droplets of water which may be retained on the dishes and other articles. The increase vin `temperature of the articles by absorption of heat from Ythe final rinse water also improves the effectiveness of lthe hot-air drying cycle which follows.

.p The illustrated-mechanical embodiments ofthe invention relate specifically to means .for forming the laterstage solutions by mixing with unheated clear Water, approximately one-half of the detergent solution remaining from a previous wash and discarding .the remainder of saidl previous detergent solution.

Other features and advantages ofthe invention will be apparent from the following detailed description of the preferred embodiments'read in connection with the accompanying drawings, in which:

Fig. 1 is a front elevation of a dishwasher embodying my invention, with certain portions of the dishwasher .housing and vat broken away to reveal underlying structure;

Fig. 2 is a. fragmentary side elevation thereof;

. Fig. 3 is a plan section, looking in the direction of the arrows 3-3 of Fig. 1;

Fig. 4 isa side sectional elevation of the drainage system shown in Fig. 3;

Fig. 5 is a detail of the supplemental drainage tube;

Figs. 6, 7, and S are details of a detergent dispenser which may be used in dishwashing apparatus embodying the present invention;

n Fig. 9 is a side elevation, in section on lines 9-9 of Fig. l, showing a suitable arrangement of the timing and other control mechanism;

Fig. is a schematic control circuit diagram for the dishwashing apparatus of the type shown in Fig. 2;

Fig. 11 is a front elevational view, partly in section, of a second embodiment of dishwashingapparatus; s

Fig. 12vis'a top plan view of a drainage systemk employedin the dishwashing apparatus of Fig. 11;

Fig. 13 is a side elevation of a valve mechanismsuitableV for4 use with the drainage system of Fig. 12; and

Fig. 14 is a schematiccontrol circuit for the dishwashing apparatus of Fig. 11.

General description Referring now to Figs. l and 2 of the drawings, the dishwasher apparatus 1 is of thegeneral type of that disclosed in my U. S. Patent 2,635,941, granted April 2l, 1953, for washing apparatus, but embodying a new drainage system, later described. The apparatus also includes a multiple detergent dispenser as disclosed in' the pending application of John C. Sharp and Leonard I. Martiniak, Serial No. 309,588, filed September 15,V 1952, now Patent 2,711,178, granted June 21, 1955, for Dishwashing Apparatus with Automatic Detergent-Dispensing Means, and assigned to my present assignee. The dishwashing apparatus cabinet 2 houses a substantially vertically disposed vat 3. The cabinet and vat have aligned front openings that are closed by a front door 4. The front door is preferably provided with ventilation louvers (not shown) as described and claimed in my said patent; and .it is pivotally mounted adjacent the lower edge thereof within the lower portion of the vat 3 so as to be movable between a substantially vertical closed position and a substantially horizontal open position. It will beunderstood that suitable means (not shown) prevent leakage of liquid about the margins of the closed door. The dishwashing apparatus has in the side walls of its vat auV arrangement or" embossed rails 3.1 on which is slidably mounted a rack R. Said rack is formed with a plurality of wire loops and other structures to support in mutually spaced relation a quantity of dishes, cups,saucers, cooking utensils,

articles of table silver, and other items (110i: shown) nor-- mally associated with the preparation and serving of a meal. In rthe following description, these articles, .of whatever nature, will be referred to merely as dishes The rack "R is movable into and out of the vat 3 through the front openings when the door 4 occupies its open position. An arrangement of this sort is described and claimed in the Forrest A. Walker application S. N. 57,448, tiled October 30, 1948, Vfor Dishwashing Apparatus and Cabinet Structure, now U. S. Patent 2,657,697, granted November 3, 1953, and also assigned to my present assignee. An impeller 5 is arranged within a sump 6 formed in the lower portion of the vat and is rotated by an associated electric motor 7 for establishing a washing action within the vat 3 by picking up liquid from the sump and discharging it in a .generally upward direction among the dishes racked within the vat.

For `supplying heated water to the vat, there is provided an inlet conduit 8 connected to a suitable source, such as the storage tank (not shown) of a water heater capable of delivering water at a temperature of the order of F. to the inlet port of an inlet valve 9 of the solenoid operated type; and the outlet conduit 10 of valve 9 communicates by way of a Y connection 11 (Fig. 2) with a conduit 12 that is connected to a vat inlet fittingsuch as a spraying device 14 arranged substantially centrally of the top wall of the vat 3. The inlet valve 9 is ofthe fast-opening, slow-closing type, being governed by an associated dashpot to prevent water hammer in the plumbing communicating with the heated water inlet conduit 8. The inlet valve 9 is normally biased to its closed position and when the solenoid 9.1 thereof is energized, the valve is operated by the lever system 9.2 to openposition to supply Water from the conduit 8 to the device 14, whereby therheated water is sprayed downwardly from the topof the vat, circulates forcefully among the racked dishes, and accumulates in the sump 6. Subsequently, when the solenoid 9.1 of the valve is de-energized, the valve moves slowly from its open position to its closed position.

For supplying unheated water to the vat, there is provided an inlet conduit 15 communicating with the cold Water supply piping (not shown) of the building, and connecting to a solenoid operated valve 16, see Fig. l, similar to the valve 9. The outlet conduit 17 of the said valve communicates by way of the other branch of the Y v Drainage control For the purpose of controlling the escape and retention of washing liquid in the sump 6, l provide primary and secondary drain systems. The primary system mayad- Vantageously be of the type disclosed in my presently pending application, S. N. 86,291, tiled April 8, 195,1, for .Drain Control Mechanism for Washing Apparatus, now U.`S. Patent 2,652,854, granted September 22, 1953, and assignedv to my present assignee. lFor example, the primary system 20Y may comprise a iiexible conduit `21, Figs. l., 3,'and 4, one end of which communicates with a drain fixture 22 provided in the lower portion of the sump 6 and the otherend of which communicates by way of a T fitting 23 with a` drain pipe 23.1 yconnected by way of a trap or the like (not shown) to drainage plumbing, not shown. Theexible conduit 21 is normally biased into its lower position in order to place the interior of the sump 6 into draining communication with the drainconduit so that any washing liquid accumulating inthe sump 6 runs through the `iexible conduit into the drainage plumbing. When the solenoid-20.1 thereof is energized, the central portion of the flexible conduit 21 is elevated into a'raised position in order to cut o Vthe draining communication between the interior of the sump 6 and the drainage plumbing, so that washing liquidmay be retained in the sump. Subsequently, when the solenoid 20.1 istie-energized, the drain conduit 21 returns automatically to its draining position. The T iitting 23 is provided with a vent pipe 23.2 to prevent air or vapor lock.

The secondary drain system may comprise a simple standpipe 24 communicating directly with the T fitting 23, as shown in Fig. 4. The standpipe passes through the bottom wall of the vat 3 adjacent the sump 6 and of course the joint between the wall of the Vat and the standpipe is made water-tight by any suitable means. An inlet opening 2S near the upper end of the standpipe faces the sump. A ventilated cap 26 prevents iniiow of liquid except through the opening 2S. Said cap may be screened, as indicated at 26.1, Fig. 5. As is well understood in the dishwasher art, when the impeller 5 is rotating during the washing and rinsing operations, the washing or rinsing liquid is thrown violently about by the impeller, and although the usual quantity of water in the vat at those times is of the order of l2 pints, and, as such, suiiicient to submerge the inlet opening only a small portion of it is actually in the sump 6 or evident on the bottom of the Vat 3 about the standpipe when the impeller is operating. The liquid returning to the sump is quickly caught up by the impeller and thrown upwardly through the stacked dishes. The return to the sump is mainly a matter of iiow in relatively thin sheets along the side walls and bottom of the Vat and along the inner panel of the front door. There is also, of course, a considerable amount of drippage from the dishes directly into the sump.

In any event, the relatively shallow layer of water passing about the pipe 24 will not overflow in any substantial amount into the opening 25 thereof. When the impeller is operating and the primary drainage system 20 is in non-draining position, very little liquid will escape from the vat into the drain pipe 23.1. When the impeller is still and the primary drainage system is in non-draining position, the liquid accumulates in the sump and in the bottom portion of the vat communicating therewith. As the liquid rises to the opening 25, it passes through pipe 24 to the drainage fitting 23. By an appropriate location of the standpipe and its opening 25, approximately one-half of the liquid in the vat may be caused to pass through the opening 4before the level of free liquid falls below said opening. There will thus be left in the vat approximately six pints of liquid for reuse as later described.

For the purpose of drying the dishes and other utensils supported by the rack R within the vat 3, the-re is preferably provided a heating unit 28 of the sheathed resistance conductor type. Said heating unit is disposed in the lower portion of the vat surrounding the impeller 5 so that air circulated over the heating unit by the blades of the rotating impeller abstracts heat from the unit and then circulates among the dishes to dry the same.

Detergent introduction Within a depression formed in the inner door panel 4.1, there is mounted a multiple detergent dispenser 29 as disclosed in the above noted Sharp andV Martiniak patent. The dispenser is formed with two chambers, 29.1 and 29.2, as best appears in Figs. 6 and 7, opening toward the interior of the vat 3, and each chamber is arranged to receive a charge of powdered detergent. Pivotally mounted on the front of the dispenser is a gate 29.3 having two water receiving cups 29.4 and 29.5; the pivot point is in the wall separating said cups as shown in Fig. 6. The gate is arranged so that the weight of cup 29.4 rotates the gate into the position in which a wall of said cup covers the chamber 29.2. A ange 29.6 at the top of cup 29.4 freely lits behind a wall 29.7 of the dispenser (see Fig. 8) and the combination of the top wall and the interiitting iiange and wall formation prevents water from entering chamber 29.2 while the gate is in its closed position. It will' be noted that there is a drainage opening 29.8' atV the bottom of cup 29.4; said drainage opening is protected by the removable screen 299 against clogging byv particles of food soil which may enter the cup 29.4 during theoperation of the dishwasher.

When the user returns the loaded rack R to the vat, he places a substantially equal charge of detergent in each of the chambers 29.1 and 29;2, moves the gate to its Fig. 6 position and closes the door 4. In anticipation of the hereinafter detailed description of the control mechanism and operation of the dishwasher, it may be noted here that the operation of the detergent dispenser is as follows:

During the preliminary rinse period when the drain valve is in its drainage position, the water passing among the dishes stacked in the rack R does not produce a iiow pattern sufficient to cause any appreciable amount of water to enter the chamber 29.1 and the detergent therein is substantially undisturbed. When the drain valve is closed (that is, moved to non-draining position) water accumulates within the sump 6 and is thrown violently among the dishes; there is at thistime a total quantity of about 12 pints of water within the vat and there is a strong water action within the vat. Water iiows into the open chamber 29.1, bringing the detergent into solution to produce, quickly, the desired washing liquid within the vat. During this operation, the respective cups 29.4 and 29.5 are being filled with Water, and because the water is entering cup 29.4 faster than it may drain through the opening 29.3, the gate 29.3 will remain in its Fig. 6 position in which the detergent in chamber 29.2 is adequately protected against water action. Following the first washing operation, which may last for two minutes or more, the impeller is stopped and the drain valve returned to drainage position. During the drainage interval the spent washing liquid is evacuated from the vat, and during said period, also, water is escaping from the cup 29.4 through its drainage opening 29.8. The gate then attains a condition wherein the water remaining in cup 29.5 overbalances the gate, which rotates to the Fig. 7 position and exposes the detergent charge in chamber 29.2. During a subsequent washing action, Water enters the chamber 29.2 and causes the detergent charge therein to -be introduced` into the vat 4 to provide a second substantially fullstrength, washing solution.

Operational cycle and control system The following operational cycle (it being understood that the time charged against each individual operation is by way of example only) produces excellent dishwashing results and minimum spotting of glassware with the machine of the Fig. 2 embodiment using detergent of the type sold under the trade name Calgonite, cornprising about 40% hexamethaphosphate or similar material, about 55% sodium metasilicate, and about 1% of an appropriate wetting agent:

A. Heated water inlet valve open for 45 second spray rinse; drain open; impeller operation optional.

B. Close drain valve; heated water inlet valve remains open to admit full amount (approximately 12 pints) of heated water and eiiect addition of detergent; impeller in operation.

C. Close inlet valve and wash for two minutes.

D. Gpen drain valve for complete evacuation of Wash liquid. impeller operation optional, but preferably still.

E. 45 second heated water spray rinse to remove residue from dishes and walls of vat; drain open; impeller rotation optional.

F. Close drain Valve fat end of spray rinse.

G. With impeller running, open unheated water inlet valve to admit full amount of unheated water and` effect addition of second detergent charge.

H. Close inlet valve and wash fortwo minutes.

Stop impeller, permitting secondary drain facility to evacuate about one-half of the wash liquid.

I. Start impeller;A open inlet valve to add unheated make-up Water to reestablish 12 pints of wash liquid.

K. Close inlet valve and Wash for two minutes. Repeat u," J,- aire x for additional washings with successively weakened detergent solutions.

L. Stop impeller; open drain valve for complete evacnation of final wash liquid.-

M. Close. drain valve y l Y N. Statt impelle; operi heated water inlet valve to add 'app'roximate'ly 12 pints of heatedl clear water for rinsing.-

O. Rinse for two minutes, with impeller rotating.

P. Stop impeller; open drain valve for complete evac nation of rinse water.

Q. Drying operation with heater on coincident with admission of nal rinse water' or following end of final rinse, as desired. Impeller operating through major portion of drying period.

The foregoing sequence of operations and modifications thereof may be accomplished by appropriately contoured switch operating cams in a suitable timer-motoroperated program selector switch, based for example on the disclosure of the Ralph L. Berg Patent No. 2,536,256,

granted January 2, 1951, for Program Selector Switch,

or on other types of switches now well known in the art. The cam operated switches of the program selector switch (hereinafter referred to as the timer) will effect the properly coordinated operation of the impeller motor 7, inlet valves 9 and 16, drain valve 29, and heater 28, to accomplish the desired operational program. lt will be assumed that the apparatus and control devices are powered from a common source of electric power, usually 115 v. 60 cycle A. C.

The timer 30 is conveniently mounted at an upper portion of the cabinet exteriorly of the vat 3, as shown in Figs. 1 and 9. It is appropriately wired in a circuit control network including the motor 7, the solenoids 9.1, 16.1 and 20.1, the heating element 28, and the measuring coil or relay R49. It is often the practice to include in the control circuit a door-operated switch (not shown) which comprises merely a switch wired into one side of the line and operated by the door 4 from a closed circuit position effected by Vclosing the door to an open circuit position as the door reaches an ajar position as it is being opened. Such a switch exercises aprimary control over the operation of the machine and insures, for example, that all operationsy will be stopped -at any mid-cycle position to permit ,one to open the dishwasher door to add articles to be washed, ete. However, the door switch has no actual function in the control cycle, and it has not been included in the control circuit shown in Fig. l0. The heated water measuring coil R46 and the unheated water measuring coil R461 are also suitably supported within the cabinet 2 exteriorly of the vat, preferably convenient to an insulated connector block B comprising a back panel of a connection box at a low point of the casing.A The respective measuring coils are of the 4marginal relay type, each being provided with an armature (not shown) respectively controlling a pair of contacts 41V and 41.1 in the control circuit. The timer housing provides journaling points for the rotatable shaft 31 which projects forwardly through an opening provided in the front wall of the cabinet. A manual control knob 32 is removably secured to the'end of said shaft and carries a pointer 33 which cooperates with indicia such as the off index and the on index marked on an escutcheon plate 34 xed to the cabinet wall. There is a second rotatable shaft 35 and a stub shaft 3e appropriately journaled .within the housing. These shafts are adjacent shaft 31 and carry a friction clutch 37 Vof any conventional design permitting shafts 35 :and 36 to be rotated 'relative to' eachother. Shafts 31 and 35 are interconnected by gearing. including the meshed pinions 38 and 38.1. Pinion 38 is secured to' shaft 31 `and has N times as many teeth as the pinion 38.1 secured tof shaft 3S. Timer 30 is driven by a motor unit 39 of the well known Telechron`type driving shaft 36 at a rate of N revolutions per hour by means of suitable intermediary speed reducing gearing. By reason of the piuions 38 and 38.1, shaft 31 is rotated at l:N revolutions per hour. The friction clutch 37 permits the shaft 31 to be manually rotated by means of the knob 32 Without damage to the motor unit 39. As later appears when the shaft 31 is manually rotated slightly more than 6@ degrees, pointer 33 is brought from its off index to the: on index and the dishwashing cycle begins.

Two insulated cams C1 and C2 are rigidly secured tox shaft 31 and respectively cooperate with the sets of switch springs diagrammatically illustrated at S1 and S2. Simi? larly, three insulating cams C3, C4 and C5 are rigidly secured to the shaft 35 and respectively cooperate with; sets of switch springs diagrammatically illustrated at 53,. S4 and S5. The contacts X and Y of the timer switch S1 may be referred to las timer contacts and the contacts of switches S2, S3, S4 and S5 as switching con-V tacts. It will be noted that in switch S1, timer contacts` vX are closed before contacts Y, and contacts Yy are opened before contacts X in the two movements@ of the main spring of said switch. Each of the switchesl 52, 53, and S4 is of the single pole, double throwv type, and switch S5 is of the single pole, singlethrow type. For simplicity of illustration, the pinions 38 and' 38.1 are in 1:1 ratio, although it will be understood that in practice cams C3, C4 and CS would be driven vat twice or three times the speed of cams C1 and C2 so as more effectively to use the peripheries of said cams C3, C4 and C5.

In the off position of knob 32, cam C1 establishes switch S1 with its contacts X and Y in open circuit condition; cam C2 establishes switch S2 with its contacts l and 2 in open circuit condition; cam C3 establishes switch S3 with its contact l closed and its contact 2 open; cam C4 establishes switch S4 with its contacts l and 2 in open circuit condition; and cam CS establishes switch S5 with its contacts in open circuit condition.

vIt will be understood that rotation of shaft 31 to its on position has the effect of moving the diagrammatic representations of the cams to the left relative to the -sets of switch springs and that the timer motor drive continues said `cams in their leftward movement. When shaft 31 is brought to its on position, therefore, the lowermost spring of switch S1 is engaged by the high portion of :cam C1 closing the contacts X and Y of switch S1; and the intermediate spring of switch S2 drops to the lowest position of cam C2 causing closure of the `contacts l of said switch. Also at this time, the intermediate spring of switch S3 is on the lowest portion of cam C3 maintaining the closed circuit position of contacts 1 of `said switch S3; in the set of switch springs S4, `the intermediate spring is on the median point of cam C4 maintaining the contacts 1 and 2 of said switch S4 in open circuit position; and in the set of switch springs S5, the upper spring is engaged by the high portion of cam C5 which causes sepa-ration of the associated contacts.

These switch relationships establish an operating circuit, as follows:

Conductor 42.1, contacts Y of switch S1, conductor 44, contacts l of switch S3, conductor 46, motor 7 and conductors 43 and 42. The impeller is then being rotated by motor '7 at its operating speed. Also in switch S1, the closure of `contacts X energizes the timer motor'39 through the obvious circuit. After a brief in'- teval, a high portion of cam C3 engages the intermediate spring of the set ofswitch springs S3 to separate the contacts l and close the contacts 2 thereof. When said contacts l open, the previously traced circuit energizing motor 7 is interrupted and the conductors 44 and 46 no' lon-ger vlprovide the shuntv circuit for thel i easurmg coils R and R401. Instead, the motor operating circuit includes the measuring coils; the circuit may be traced from conductors 43 and 44 through contacts Y of switch S1 to the neutral conductor 42.1. The measuring coils, each comprising a marginal relay, will not open their contacts at this time, because there is no water in the sump 6 and the current demand of the motor 7 is light.

The closure of contacts 2 of switch S3 completes a circuit to energize solenoid 9.1 of heated water inlet valve 9; said circuit includes conductor 42.2, contacts l of switch S2, conductor 47, solenoid 9.1, closed contacts 41 of the measuring coil R40, conductor 49, contacts 2 of `switch S3, conductor 44, timer contacts Y, and conductor 42.1. Solenoid 16.1 of the unheated water inlet valve 16 `will remain de-energized because the control contacts 2 of switch S4 are open.

Energizing the solenoid 9.1 operates the inlet valve 9 to open position, whereuponk heated water is supplied to the vat inlet device 14. T he water sprays downwardly through the stacked dishes and enters the sump 6. Some or" the water is caught by the impeller and ung against the dishes, aiding in the removal of loose soil. The rinsing liquid drains throught the drain valve organization 20, it being then in its drain position. The first spray operation continues for about seconds, as previously noted.

As the conclusion of this spray operation, the upper spring of switch S5 drops to a low point of cam C5, closing a circuit which energizes solenoid 20.1 to operate the drain valve to closed position. This circuit includes conductor 42.2, contacts l of switch S2, conductor 47, solenoid 20.1, conductor 48, switch SS, conductor 44, timer contacts Y, and conductor 42.1. The liquid continues to enter the vat through the inlet device and accumulates in the sump. The impeller 5 is still operating; and as the load imposed upon motor 7 increases, the current traversing the motor and the measuring coils increases. When the vat has accumulated the full quantity of washing liquid (approximately l2 pints), the current drawn by the motor is at the operating level of the respective measuring coils, lwhich thereupon open their respective contacts. The opening of contacts 41 interrupts the circuit to the heated water inlet valve solenoid 9.1 and water inow ceases.

The measuring coils insure that the inlet will remain open until the proper iill is made even though low water pressures may reduce the rate of inow of water. If domestic water Ipressures Iwere uniform throughout the country, a simple time control would sufice for a ll valve having an orifice -calculated to deliver the desired amount of water to the vat in a predetermined amount of time. As a safety measure against failure of coil R40 to open its contacts 41, however, cam C3 is congurated to cause the intermediate yspring leaf of switch S3 to open its contacts 2 and close its `contacts 1 about 45 seconds after the drain valve has been operated to non-draining position. This re-establishes the original direct motor circuit for motor 7 and again shunts out the measuring coils, which thereupon drop the respective contacts 41 and 41.1, to closed circuit position. This is without etect on the heated water inlet valve, because the circuit to the solenoid 9.1 thereof is broken at the contacts 2 of switch S3. lt is likewise without effect on the unheated water inlet valve. The rst washing step continues for about two minutes during which time the water evacuates the detergent from chamber 29.1 and provides within the vat an eecti've detergent solution.

At the conclusion of the rst washing step, a high point of cam C5 engages the Vspring of switch S5, opening the contacts of said Iswitch and thus interrupting the circuit to the drain valve solenoid, whereby the drain valve returns to draining position. It is advantageous to stop the motor 7 during this drainage in order to prevent redeposition of soil on the dishes. Accordingly, cam C1 is congurated to drop the lower-most spring of the 10 set of switch springs S1 to eiectthe opening' of con. tacts Y thereof, thereby' breaking the motor circuit Without interrupting the timer motor circuit established by contacts X. The liquid drains quickly from the vat. At this stage, cam C1 again closes the timer contacts Y to re-energize the motor 7 to drive the impeller associated therewith. Also at this time, the `contacts 2 of switch 'S3 are closed, re-establishing the measuring coil in the rnotor circuit and energizing the heated water inlet valve coil 9.1 in the manner previously explained. The dishes are again sprayed with heated rinsingwater for approximately 45 seconds during which the drain valveA is open. Cam C3 thereupon drops the central spring of switch S3 to the intermediate position at which contacts l and 2 of said switch are open. The drain Valve is closed as the spring of switch S5 drops to the lowl point of cam C5 again to complete the circuit to the drain valve operating Isolenoid 20.1. In overlapping relationship with the operation of cam C3, cam C4 rises from its intermediate position to close contacts 2 of switch S4, energizing the unheated water inlet lvalve coil 16.1. This admits unheated ywater into the vat. The measuring coil R401 assumes primary control over the quantity of water introduced, but after about 45 seconds, the intermediate spring of yswitch S4 drops to a low point of cam C4 to open the circuit to solenoid 16.1, and establish the motor circuit through conductors 42, 43, motor 7, conductor 46, contacts l of switch S4, conductor 44, contacts Y of switch S1, and conductor 42.1. The second washing operation is then under Iway and the second charge of detergent mixes with the unheatedV water to form a second substantially full strength, detergent solution.

As indicated by the foregoing schedule of operations, only about one-half of the washing solution is to be discarded at the end ot this second wash period. This is accomplished by stopping the motor 7 to permit the solution to How into the drain pipe 23.1 only through the standpipe 24. As previously noted, the inlet to said standpipe is so placed that when about one-half of the liquid has discharged to the drain, the level of the liquid remaining in the sump will be below the inlet. Cam C1 is contigurated to maintain the open circuit of' the motor as previously described for a time interval insuring desired drainage. The motor starts again, and substantially coincidentally therewith cam C4 again closes contacts "2 of switch S4 to energize the inlet coil solenoid 16.1. It is obvious that a shorter ll time is required for completing the ll for the next wash period. The duration of the closure of contacts 2 of switch S4 may be suitably shortened, although with the fill control provided by the measuring coil R401, the closure periods may be kept uniform if desired. Cam C4 then causes contacts 2or` switch S4 to open, and contacts "1 thereof to close, shunting out coil R401 and breaking the circuit to coil 16.1.

A third wash then proceeds with an unheated water detergent solution. The solution is at approximately one-half strength, but is nevertheless eiiective to support the food soil remaining in the vat after the preceding washing and rinsing operations.

A fourth and fifth wash with successively less concentrations of detergent are carried out in the manner described above. At the end of the fifth wash, however, the drain valve solenoid is energized to effect complete removal of the final wash liquid. As previously, the motor is de-energized during draining. Cam C4 iinally causes the intermediate switch spring of switch S4 to place both of the contacts l and 2 thereof in open circuit condition, inactivating the unheated water inlet valve.

The motor is then restarted and very shortly thereafter, heated rinse water is introduced Iby the action of cam C3, and after a till period as previously described, cam C3 drops to close contacts 1 of switch S3, maintaining the motor circuit but inactivating solenoid 9.1. In suitable relation Vto the introduction Vof heated rinse water, cam C causes the contacts of switch S5 to close the circuit to solenoid 20.1. As previously, the energized solenoid operates the drain valve system to nondraining position.

At the end of a. final power rinse period of about two minutes, the drain valve solenoid is again de-energized, permitting complete and final drainage of the liquid from the machine. The motor 7 remains in operation. At this time, or prior thereto if desired, cam C2 opens the contacts 1 of switch S2 and closes the contacts thereof, thus completing a circuit to the heating element 28. The motor 7 and timer motor 39 remain in operation by reason of the continued closure of contacts X and Y of switch S1 and the impeller is therefore effective to circulate heated air among the dishes to facilitate the drying thereof. After a Suitable interval cam C1 causes the contacts Y of switch S1 to open, thus interrupting the motor 7 circuit while maintaining closed the circuit of timer motor 39 through contacts X of said switch. Drying then continues without air circulation for a predetermined time at the end of which the cam C1 opens contacts X of switch S1 and cam C2 restores both contacts of switch S2 to open circuit position. `This operation coincides with the completion of the full rotation of the cams and the return of the pointer 33 to oft position.

Although at the completion of the several washing opcrations of the complete operational cycle, there is so little food soil remaining in the final washing solution that a clear unheated water rinse would adequately serve the mechanics and objectives of the final rinse, I prefer the heated water rinse because of the lower surface tension of heated water as compared to unheated water, and the lessened possibility of retention of large drops on the dishes. Also, the heat released by the water raises the temperature within the vat and in this way assists the heating element in its drying function.

The total elapsed time for washing and rinsing is of the order of 25 minutes and the remaining time represented by the cam chart is devoted to drying. The friction clutch of the time control mechanism makes it possible manually to advance the control knob to eliminate or shorten any phase of the operation, asis now well understood in the art.

A seco/ld embodiment ln the embodiment of Figs, 1l through 14, -all elements in common with the Fig. 2 embodiment carry the same reference characters. In lieu or" the drain valve organization of Fig. 2, however, the drainage system of the present embodiment comprises a tank 60, the capacity of which is more than one-half of the full washing liquid charge of twelve pints,a pipe 6i communicating between said tank and the trap tting 62, a valved pipe 63 from the sump 6 to the tank 6d), and a valved drain 64 communicating between pipe 63 upstream of its valve and entering the trap fitting 62 below the tank. Pipe 61 performs a function similar to that of the standpipe 24 of the earlier embodiment, in that when all of the wash water is brought into the tank, about one-half of it will overow into the pipe 61 for elimination. This makes the remainder of the liquid available for reuse as presently described. The provisions for the introduction of heated and unheated water are retained because such an arrangement is representative of the preferred ernbodimcnt of the invention. It should be understood, however, that all washing `and rinsing operations may be carried out with heated water only. The primary 0bjective of hot water economy is realized by the retenvtion of approximately one-half of the previous washing solution and the resulting necessity for adding only a one-half portion of fresh water to restore the full volume of washing liquid. Y

VValve in pipe 63 and valve 66 in drain 64 may be of any conventional solenoid operated gate type, although I prefer appropriate structural modilications of the valve shown in my Patent 2,271,993, granted February 3, 1942, for Valve Construction for Washing Apparatus. The valves respectively have the solenoids 65.1 and 66.1 and spring biased'as by the coil spring or equivalent 65.2, Fig. 13, when the associated solenoid is de-energized, to establish the valve element thereof (not shown) in a free swinging position which corresponds to a normally open condition.

The eluent remaining in the tank 60 is made available for reuse by a pump 67 having its intake 68 communicating with the tank and its discharge connected by means of the tube 70 to an inlet iitting 71 of the device 72 through which the liquid is introduced into the vat. A second inlet portion of the device 72 comprises the terminus of the conduit 12 to which the outlet ports of the respective heated and unheated water inlet valves are connected as previously described. Tthe pump is driven by a suitable motor 73, shown in Fig. 12 as mounted directly on therpump casing. It will be understood, of course, that the tank 60 is suitably vented as by the vent tube 60.1 which rises Within the outer casing of the dishwasher to a point substantially above the maximum free water level in the vat.

It will therefore be seen that the valving arrangement of the drainage system of the present embodiment makes it possible completely to discharge to the plumbing drain, the effluent from a previous operation or to retain approximately one-half of the etuent for reuse in a future operation. Any number of complete drainages may be interposed between the operational stage at which the effluent is stored for reuse, and the actual time of such reuse.

The features of the instant embodiment will be apparent from the operational diagram of Fig. 14. With respect to said diagram, it may be noted that for simpli cation, all inlet valves are considered to be open for a Xed time interval calculated to provide the necessary quant-ities of water. It will be understood, however, that the circuit may be ,established to include, if desired, the measuring coil control system embodying the marginal relays R40 and R40.1 previously described.

It will be assumed that the control has a manual adjustment knob, such as the knob 32 of the earlier embodiment, and -a timer motor 39 driving a series of cams arranged on one or more cam shafts within the control casing. Switch S1.1 controlled by cam C1.1 has a switch spring stack in vwhich the lowermost switch spring will lirst close the Y contacts and then the X contacts as said spring rises on the cam, and will open these contacts in reverse order as the spring descends on the cam; and the single sets of switch springs of the remaining switches S 2.1 through S7.1 will operate to closed or openposition as the indicated springs thereof follow the cam contours.4 j

' Assuming that rotation of the knob 32 to its on p osition has the effect of moving the cam bank to the left, as viewedin Fig. 14, and that the operation of timer motor 39 continues such leftward movement, it will be noted that as the intermediate rise portion of cam C1.1 engages and lifts the indicated spring of switch $1.1 the timer motor is energized across line conductors and 80.1 through contacts Y of switch 81.1 but the main drive motor 7 is not energized because the contacts X of said switch are not closed.

In suitable timed relation therewith, the uppermost switch spring of switch $3.1 drops as it follows a downslope on cam C3.1, thus energizing the heated water. inlet solenoid 9.1 to admit clear, heated rinse water through tube 12 to the inlet fitting 72, lwhence it flows about the dishes in the rack (not shown) and enters the sump 6. This is known in the art as a spray rinse. The impellerS is Anot rotating during thisrinsing operation. A1-

though motor operation during the spray rinse is optional, many prefer that the impeller be still, so as to avoid the redeposit of soil removed by the spray action. Switch 55.1 holds open the circuit to solenoid 66.1 by reason of the contour of cam C51 and Valve 66 remains open to permit all of the rinse water to pass through pipe 64 to the plumbing waste line. Solenoid 65.1 is energized by reason of the relation of cam C61 to switch S61, and its associated valve 65 is therefore held closed. Pump motor 73 is inactive. At the end of about 45 seconds, cam C5.1 causes the contacts of switch $5.1 to close energizing the solenoid 66.i and positively closing the valve 66. The contacts of switch 53.1 remain closed however for a further period of 45 seconds (it being understood that this has been arbitrarily selected as the length of time an inlet valve should remain open to admit the full l2 pint charge of water) to accumulate the first required quantity of heated wash water. Cam C11 closes the contacts X of switch $1.1, energizing the motor 7 to drive the impeller and thus produce the Water flow necessary to wash the first detergent charge out of chamber 29.1 of the detergent dispenser. The secondwash detergent charge is protected by the gate 29.3 as previously described.

At the end of the time allowed to the first wash-for example, two minutes-cam Cil causes the separation of contacts X of switch SM while continuing contacts Y thereof closed. The drive motor 7 circuit is thus opened while the timer motor 39 circuit remains closed. Cam C51 again causes switch S51 to open the circuit to solenoid 661 and the spent wash liquid passes through pipe 64 to the plumbing drain. Allowing -a suitable time-say, 45 seconds-for complete drainage from the vat, all of the gross soil sequestered and supported by the first detergent solution will have passed from the vat with said solution. Valve 66 remains open, however, while cam C31 closes the contacts of switch $3.1 to energize the heated Water inlet valve solenoid 9i for another spray rinsing period. The impeller remains out of operation. At the end of this second heated water rinse, :am CLl closes the circuit to motor 7, the circuit to heatd water inlet valve solenoid 91 opens and the circuit o the unheated water inlet valve solenoid 16.1 will be closed to effect the introduction of unheated water for the second washing operation. As clearly appears in Fig. 14, cam C51 closes the contacts of switch 85.1, energizing solenoid 66.1 to close valve 66. Valve 65 remains closed.

During the second washing operation, the detergent in amber 29.2 is brought into solution with the unheated .vater to provide a second washing solution substantially equal in strength to the iirst solution. The termination of the second wash is signified by the opening of the motor circuit to halt impeller rotation, and the opening of valve 65 to admit the Washing solution to the tank 6i), in which approximately one-half will be retained, the remainder escaping through pipe 6i, as previously eX- plained. Valve 65 opens upon de-energization of solenoid 65.1 as cam C61 opens the contacts of switch 56.1, whereas valve 66 remains closed by reason of the continued energization of solenoid 66.1.

After an appropriate drainage period, cam C61 again energizes solenoid 655i to close valve 65, and cam C51 opens the contacts of switch 85.1, de-energizing solenoid 66.1 and causing valve 66 to be in open position. At this time, cam C4.1 closes contacts 54.2 to energize solenoid 16.1, and for a period of about 45 seconds, clear, unheated rinse water is introduced into the vat. The irnpeller is not operating. r`he dishes are again thoroughly spray rinsed for a third time.

At the end of this third rinse period, solenoid 66.3 is energized for closure of its associated valve 66. Cam C11 operates to return the impeiier to operation and cam C41 maintains the switch contacts S41 ciosed. Soienoid 16.31 continues energized to maintain the inow of unheated water.v Also at the end of the rinse period,

cam C7.1 closes the contacts to switch $7.1, energizing the pump motor 73. The portion of the second wash liquid in tank 60, representing about one-half of the total wash liquid as above explained, is thus pumped through fitting 72 into the vat where it mixes with the incoming charge of unheated, clear water. After about 25 seconds--a period which, for purposes of illustration, represents the time required to introduce approximately 6 pints of unheated, clear water and to empty the tank -cams C41 and C7.1 cause their respective circuits to open. This third Washing liquid contains only that detergent which was present in the retained second wash liquid, but the resulting detergent solution is adequate in view of the small amount of food soil remaining on the dishes and vat walls. At the end of the third wash, valve 65 is permitted to open to direct the ethuent into tank 6ft. Valve 66 remains closed.

A fourth and fth wash may thereafter follow, with no rinses after the third and fourth wash periods. Between the third and fourth and fourth and fifth washes, therefore, only the valve 65 is operated. As previously noted, the operation of the impeller during any drainage operation is a matter of preference. In preparation for the fourth and fifth wash operations, the unheated water inlet valve is opened at appropriate times to add 6 pints of clear water to the 6 pints of liquid transferred bythe pump from the tank 64) to the vat inlet 72.

At the end of the fifth wash, the impeller is stopped, and valve 66 is opened to effect complete removal of the last washing liquid. Valve 65 is of course closed. The dishes are then given a final heated water fpower rinse with the impeller operating. Valves 65 and 66 are closed. At the end of the final rinse period, the motor may, if desired, be stopped, and valve 66 opened, t0 elfect complete drainage. The motor is thereafter started and cam C2.1 closes the circuit to heating element 29. A drying cycle thereupon proceeds as previously described, and near the end of the complete cycle cam C11 drops the spring leaf of switch 81.1 to an intermediate position which opens the circuit to the motor 7. The timer remains in operation, and at the end of the drying period cam Cll.1 drops to open contacts Y of switch Sli and cam C21 opens the heating coil circuit.

The complete operational cycle has then been conipleted and the dishes are ready for removal from the machine.

From the foregoing descriptions, it is apparent that dishwashers embodying the inventions provide methods of washing dishes in which the dishes are subjected to multiple washes with detergent solutions having temperature and detergent factors suitable for the conditions existing at a particular phase of the operation; and that said multiple washing operations are carried out economically, as respects expenditures of water and detergent.

While there have been described what is at present considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

l claim:

1. The method of washing dishes arranged within a washing vat, comprising the steps of rinsing the loose soil from the dishes by circulating rinsing liquid among the dishes while effecting continuous drainage from the vat; introducing into and retaining in said vat a quantity of water having a temperature of the order of F., mixing with said water a quantity of detergent to provide a rst detergent solution and circulating said solu tion among the dishes for a rst predetermined period; rinsing the dishes a second time by circulating rinsing liquid among the dishes while again effecting continuous drainage` of'sad rinsing liquid from said vat; introducing into and retaining in said vat a quantity of water having a temperature less than 100 F., mixing with said water a quantity of detergent to form a second detergent solution and circulating said solution among said dishes for a predetermined period; draining said solution completely from the vat; introducing into and retaining within said vat a quantity of rinsing liquid substantially equal to the quantity of the second detergent solution and circulating said liquid among the dishes for a predetermined period; stopping said rinsing liquid circulation; and permitting said rinsing liquid to drain from the vat substantially coincidentally with the interruption of said rinse liquid circulation.

2. The method of Washing dishes arranged in mutually spaced relation in a Washing vat, comprising the steps of rinsing the loose soil from the dishes by circulating rinsing liquid among said dishes while effecting continuous drainage from said vat; introducing into said vat a quantity of heated Water and a quantity of detergent and circulating the resultant mixture among said dishes for a predetermined interval while substantially preventing drainage from said vat; permitting said mixture to drain from the vat; rinsing said dishes with clear water; draining said rinse Water from saidvat; introducing into said vat a quantity of unheated water and a second quantity of detergent and circulating the resultant mix ture among said dishes for a predetermined interval while substantially preventing drainage from said vat; interrupting said circulation and draining the mixture from said vat; introducing into said vat and circulating among said dishes a quantity of heated rinsing Water fand iinally draining said rinse Water from said vat.

3. The method of Washing and drying dishes arranged in mutually spaced relation in a Washing vat, comprising the steps of rinsing the loose soil from the dishes by circulating heated rinsing liquid among the dishes and permitting said rinsing liquid continuously to drain from the vat; introducing into said vat a quantity of heated water and a quantity of detergent and circulating the resultant mixture among said dishes for a predetermined period; permitting said mixture to drain from said vat; introducing into said vat a quantity of unheated rinsing liquid and permitting the same to permeate the dishes to abstract heat therefrom; draining said rinsing liquid from said vat; introducing into said vat a quantity of unheated Water and mixing the same with a quantity of detergent to provide a second washing mixture substantially equal in volume and detergent concentration as the rst Washing mixture; circulating said second washing mixture among the dishes for a predetermined interval; removing said second washing mixture from the vat; raising the temperature of the dishes within the vat by circulating therein a quantity of heated rinsing liquid; draining said rinsing liquid; and linally circulating air among the dishes to evaporate the moisture therefrom.

4. The method of washing dishes arranged in mutually spaced relation in a Washing vat, which includes the .steps of rinsing the loose soil from said dishes by circulating heated rinse liquid among said dishes; intro ducing into said vat a quantity of washing liquid and 'circulating said liquid among said dishes for a predetermined interval during which substantially all of said liquid is maintained in said vat; draining from said vat substantially one half of the said quantity of washing liquid; introducing into said vat a quantity of Washing.

liquid sucient to increase any undrained portion of the irst washing liquid substantially to the initial quantity of said rst liquid and circulating the same among said dishes while substantially preventing drainage of said liquid from said vat; again interrupting said circulation while permitting complete drainage of said liquid from said vat; introducing rinsing liquid into said vat and circulating the same among said dishes while substan- 1li tially preventing drainage from rsaid vat; draining said rinsing liquid from said vat; and permitting 4said dishes to dry While remaining in said vat.

5. The method of washing dishes arranged in vmutually spaced relation in a Washing vat, comprising the steps of rinsing loose soil from said dishes by circulating rinsing liquid among said dishes While eiecting continuous drainage from said vat; introducing into said vat a quantity of detergent solution and circulating said solution among said dishes for a predetermined interval during which drainage from said vat is substantially prevented; interrupting said circulation of said liquid and permitting the same to drain from said vat; introducing into and circulating within said'vat a second quantity of rinsing liquidand permitting said liquid to drain from said vat; introducing a second quantity of detergent solution into said vat and circulating said solution among said dishes for a second predetermined interval during which drainage from said vat'is substantially prevented; interrupting said circulation and discarding a substantially predetermined portion of said solution from said vat to retain in said vat a residual portion'of said second detergent solution to serve as the kbasis for a third detergent solution; adding liquid to said residual portion of said solution to produce a Washing'solution substantially equal in volume to said second-named solution but having a lesser concentration of detergent and circulating said resultant WashingV solution among said dishes while preventing anyY substantial drainage from said vat; interrupting said circulation and completely draining said `solution from said vat;v and thereafter rinsing said dishes with liquid containing no appreciable amounts of detergent.

6. The method of washing dishes arranged in mutually spaced relation in a Washing vat, comprising the steps of rinsing the loose soil from said dishes by circulating rinsing liquid among said dishes while effecting vcontinuous drainage from said vat; `introducing into said vat a quantity of heated detergent solution and circulating said solution among said dishes for a predetermined interval during which drainage fromsaid vat is substantially prevented; interrupting said circulation of said liquid and permitting the same to' drain `from said vat;` introducing into and circulating Within said vat a second quantity of rinsing liquid and permitting said liquid to drain from said vat; introducing into said vat a quantity of unheated detergent solution and circulating said solution among said dishes for a second predeterminedIk interval during which drainage from said vatis sub.4V stantially prevented; interrupting said circulation an discarding a substantially predetermined portion ofsai solution from said vat; adding 4liquid to the residual portion ot said solution to'produce a washing solution substantially equal in volume to said second-named solution but having a lesser concentration of detergent and circulating the resultant solution among said dishes for a third predetermined interval while preventing any substantial drainage from said'vat; interrupting said circulation and completely draining said last-named solution from said vat; and thereafter rinsing said dishes with heated liquid containing no appreciable amounts of detergent. i

7. The method of washing dishes arranged in a Washing vat, comprising the stepsV of rinsing the loose soil from said dishes by introducing rinsingliquid from the upper portion of said vat and spraying said liquid downwardly among said dishes While eiecting continuous drainage from said vat; introducing into said vat a quantity of heated detergent solution and circulating said solution upwardly among said dishes for a predetermined interval during which drainage from said vat is substantially prevented; interrupting said circulation of said liquid and permitting the same to drain from said vat; introducing into and spraying within said vat a quantity of unheated rinsing liquid and permitting said liquid to drain from said Vat; introducing .a quantity of unheated detergent solution into said vat and circulating said solution upwardly among said dishes for a second -predetermined interval during which drainage from said vat is substantially prevented; interrupting said circulation and discarding a substantially predetermined portion of said solution from said vat; -adding unheated liquid to the residual portion of said solution to ,produce awashing solution substantially equal in volume to Ysaid secondnamed solution but having -a lesser concentration of detergent and circulating said washing solution among said dishes-while preventing any substantial-drainage from said vat; interrupting said circulation and completely draining said washing solution from said vat; introducing and retaining within said vat a quantity of liquid containing no appreciable amounts of detergent and circulating said liquid upwardly among said dishes; draining said rinsing liquid; and circulating heated air among said dishes to dry them.

S. The method of washing and drying dishes 4arranged within a vat, which includes the steps of rinsing said dishes with clear water and thereafter washing said dishes with a heated detergent solution by circulating said solution mechanically over said dishes; draining said solution completely from said vat; rinsing said dishes with clear, unheated water and draining the same from the vat; washing said dishes a second time by mechanically circulating unheated detergent solution over said dishes, said detergent solution having substantiallyv the same volume as said first-named solution and substantially the same quantity of detergent therein; then vsubjecting said dishes to a succession of washing operations, using for each said washing operation a portion of the detergent solution of the immediately preceding wash and a suicient quantity of unheated water to restore the volume of liquid within the vat to substantially that of the second-named detergent solution; finally removing all of the solution from said vat; rinsing said dishes with rinsing liquid; and air drying the dishes while they remain in the Vat by circulating heated air throughout the vat.

9. Dishwashing apparatus, including a vat having means for supporting a plurality of dishes to be washed; water inlet valve means for introducing into said vat, at separated periods of a complete washing operation, a quantity or heated water and a quantity of unheated water; impeller means operable to circulate said Water about the dishes in said vat; means comprising individual containers disposed within said vat for accommodating quantities of detergent; means including said impeller means for causing said detergent to be mixed into said heated and said unheated water to provide a detergent solution; drain valve means for controlling the removal of spent detergent solution from said vat following a washing operation; and cycle-control means for eecting operation of said water inlet valve means, said impeller means, and said drain valve means in a desired operational sequence.

l0. Dishwashing apparatus, including a vat having means for supporting a plurality of dishes to be washed; water inlet valve means for introducing into said vat, at separate periods of a complete washing operation, a quantity of heated water and a quantity of unheated water; impeller means operable to circulate said water about the dishes in said vat; means comprising individual containers disposed within the vat for accommodating quantities of detergent; means including said impeller means for causing said detergent in certain of said containers to be mixed with heated water and for causing detergent in other of said containers to be mixed with unheated water, to form in each case a detergent solution; a rst drainage system for eiecting a complete drainage of detergent solution from said vat; a second drainage system for effecting only a partial drainage of detergent solution from said vat; and cycle-control means effecting operation ofV said water inlet vaive means, `said `impeller means, -and said rst and second drainage systems in a desired 'operational sequence.

ll. Dishwashing apparatus, including aV vat having `means for supporting a plurality of dishes to be washed;

inlet valve 4means for introducing into said vat, at widely spaced periods of a complete washing operation, a quantity of heated water, and a quantity of unheated water;

:impeller means for circulating said water about the dishes iny said vat; means for introducing detergent into said heated water and into said unheated Water, to establish, at said Vspaced periods, a heated and an unheated detergent solution for washing said dishes; means providing a sump in the lower portion of said vat; a iirst 'drainage means communicating between said sump and a plumbing drain 'system' to provide for complete evacuation of detergent solution; a second drainage system communicating Vbetween said sump and said plumbing drain to providel a predetermined partial evacuation ofv detergent solution; and means for operating said first and second drainage means in predetermined sequence.

l2. Dishwashing apparatus, including a vat arranged to receive -a quantity of dishes to be washed; inlet valve means for introducing into said vat quantities of water for the washing operation; means for adding detergent to said water to `provide a detergent solution; an impeller disposed in a sump portion of said Vat'to circulate said-detergent upwardly and outwardly from said sump and-among the dishes to wash the same; a rst drainage system communicating between said sump and a plumbing drain, said vdrainage system having valving means operable Atopermit or prevent the drainage of saidsurnp; a second drainage system having an open-ended standpipe communicating between said sump and said plumbing drain, said standpipe opening being substantially above the free level of said detergent solution in said sump during operation of said impeller and substantially below said free level during non-operation of said impeller whereby during periods of non-operation of said impeller and non-draining status of said first-system valving means a predetermined portion of said solution may be drained from said sump; and control means for effecting operation of said inlet valve, said impeller, and said rst-system valving means in a desired sequence.

l3. Dishwashing apparatus, including a vat arranged to receive a quantity of dishes to be washed, said vat having a sump portion at a low point thereof; inlet Valve means for introducing into said vat quantities of water for the washing operation; means for adding detergent to said water to provide a detergent solution; an impeller disposed in said sump portion to circulate said solution among said dishes; a liquid collection chamber disposed externally or" said vat and having a capacity of more than one-half of the detergent solution used in a washing operation; a conduit communicating between said vat and said chamber; a valve in said conduit and operable between open and closed positions; a standpipe in said chamber communicating directly with a plumbing drain, said standpipe having an opening within said chamber to withdraw a predetermined quantity of liquid therefrom; a second conduit communicating between said plumbing drain and said irst conduit upstream of said valve; a valve in said second conduit operable between open and closed positions to permit or prevent drainage of the liquid in said vat directly to said plumbing drain; a third conduit communicating between said collection chamber and said vat above the sump thereof; a pump in said third conduit to pump liquid from said chamber to said vat; and control means for eecting operation of said inlet valve, said impeller, said rst and second-named drainage control valves, and said pump, in a desired operational sequence.

14. Dishwashing apparatus, including a vat having means for supporting a plurality of dishes to be washed; inlet valve means for introducing into said vat a quan- 19 tity of heated water for washing dishes; inlet valve means for introducing into said vat a quantity of unheated Water for washing dishes; impeller means for circulating said water throughout said vat during said washing operations; a plurality of containers within said vat for ac-v commodating separate charges of detergent; means for introducing a charge of detergent into said heated water and into said unheatedk water, whereby to create heated and unheated Washing solutions respectively; drain valve means for controlling removal of spent detergent solution from said vat following each of said Washing operations; and cycle control means for effecting operation of the respective inlet valve means, the impeller means, and the drain valve means in desired operational sequence.

15. The method of washing and drying dishes arranged within a vat, which includes the steps of washing said dishes with a detergent solution by circulating said solution mechanically over said dishes; draining said solution completely from said vat; rinsing said dishes with clean water and draining the rinsing liquid from the vat; washing said dishes a second time by mechanically circulating a second quantity of detergent solution over the dishes, said quantity of solution being substantially the same in volume as the rst-named solution; then subjecting said dishes to a succession of washing operations by circulating over the dishes, a detergent solution comprised of a portion of the solution Vof the immediately preceding washing operation and a suicient quantity of clean water to restore the volume in each case to that of the preceding solution; completely draining and discarding the solution following the iinal Washing operation; rinsing said dishes with rinsing liquid; and air drying said dishes while they remain in the vat by circulating air throughout said vat. Y Y Y 16. Dishwashing apparatus, including a vat having means for supporting a plurality of dishes to beV washed; water inlet valve means for introducing into lsaid vat, at separated periods of a complete washing operation, a quantity of heated Water and a quantity of unheated water, respectively; means for circulating the respective quantities of Water among the dishes in said vat; means for introducing into said vat a first predetermined quantity of detergent for mixture with said heated water during the circulation thereof, and a second predetermined quantity of detergent for mixture with said unheated water during the circulation thereof, whereby to effect separated washing operations with a heated detergent solution and an untreated detergent solution; drain valve means for controlling the removal of said detergent solutions; and cycle-control means for effecting operation of said inlet valve means, said water circulating means and said drain valve means in a predetermined operational sequence. v

References Cited in the le of this patent UNITED STATES PATENTS 1,645,815 Murdoch Oct. 18, 1927 2,025,571 Clark Dec.'24, 1935 2,552,852 Idle MaylS, 1951 2,562,772 Clark July 3l, 1951 2,624,352 Illian Jan. 6, 1953 2,711,178 Sharp June 2l,` 1955 

2. THE METHOD OF WASHING DISHES ARRANGED IN MUTUALLY SPACED RELATION IN A WASHING VAT, COMPRISING THE STEPS OF RINSING THE LOOSE SOIL FROM THE DISHES BY CIRCULATING RISING LIQUID AMONG SAID DISHES WHILE EFFECING CONTINUOUS DRAINAGE FROM SAID VAT; INTRODUCING INTO SAID VAT A QUANTITY OF HEATED WATER AND A QUANTITY OF DETERGENT AND CIRCULATING THE RESULTANT MIXTURE AMONG SAID DISHES FROM A PREDETERMINED INTERVAL WHILE SUBSTANTIALLY PREVENTING DRAINAGE FROM SAID VAT; PERMITTING SAID MIXTURE TO DRAIN FROM THE VAT; RINSING SAID DISHES WITH CLEAR WATER; DRAINING SAID RINSE WATER FROM SAID VAT; INTRODUCING INTO SAID VAT A QUANTITY OF UNHEATED WATER AND A SECOND QUANTITY OF DETERGENT AND CIRCULATING THE RESULTANT MIXTURE AMONG SAID DISHES FOR A PREDETERMINED INTERVAL WHILE SUBSTANTIALLY PREVENTING DRAINAGE FROM SAID VAT; INTERRUPTING SAID CIRCULATION AND DRAINING THE MIXTURE FROM SAID VAT; INTRODUCING INTO SAID VAT THE CIRCULATING AMONG SAID DISHES A QUANTITY OF HEATED RINSING WATER AND FINALLY DRAINING SAID RINSE WATER FROM SAID VAT.
 9. DISHWASHING APPARATUS, INCLUDING A VAT HAVING MEANS FOR SUPPORTING A PLURALITY OF DISHES TO BE WASHED; WATER INLET VALVE MEANS FOR INTRODUCING INTO SAID VAT, AT SEPARATED PERIODS OF A COMPLETE WASHING OPERATION, A QUANTITY OF HEATED WATER AND A QUANTITY OF UNHEATED WATER; IMPELLER MEANS OPERABLE TO CIRCULATE SAID WATER ABOUT THE DISHES IN SAID VAT; MEANS COMPRISING INDIVIDUAL CONTAINERS DISPOSED WITHIN SAID VAT FOR ACCOMMODATING QUANTITIES OF DETERGENT; MEANS INCLUDING SAID IMPELLER MEANS FOR CAUSING SAID DETERGENT TO BE MIXED INTO SAID HEATED AND SAID UNHEATED WATER TO PROVIDE A DETERGENT SOLUTION; DRAIN VALVE MEANS FOR CONTROLLING THE REMOVAL OF SPENT DETERGENT SOLUTION FROM SAID VAT FOLLOWING A WASHING OPERATION, AND CYCLE-CONTROL MEANS FOR EFFECTING OPERATION; AND CYCLE-CONTROL MEANS FOR EFFECTING MEANS, AND SAID DRAIN VALVE MEANS IN A DESIRED OPERATIONAL SEQUENCE. 